Under normal circumstances open water swimming happens in conjunction with pool training and most of us use our open water time for something slightly different from our pool sessions: mostly some long, unbroken swimming and sometimes triathlon-specific open-water skills like sighting, drafting, starts, buoy turns, exits and transitions.
Because the Clock, that omnipresent ‘big brother’ timing every length in the pool to the second, is nowhere to be seen, the language used in the pool to describe sets and reps doesn’t quite make sense: “Hundreds on 1:45?!?”
If you’re going to be swimming only in open water for a while, and only on your own, you might want to think a little about what those sets and reps in the pool are for. They’re not just there to allow more than two people to co-habit in a lane!
Swimming and triathlon training is primarily cardio-vascular. The training effect comes from working your heart and lungs at elevated intensities for periods of time. The more sophisticated your training, the more finely tuned those intensities and periods of time are. Coaches who create group swim programmes write sessions which create a suitable balance for those in their group. The more tightly aligned the group, the more specific the tuning; the broader the group, the more generic. Where there are multiple sessions over a week the content of each session is different, and is different from the content of a single weekly session. Sessions for drop-in groups look different from those for closed groups. Triathlon group sessions as a whole look different from swimmer-only group sessions. They are different because the combinations of sets and reps are different.
Swim coaches use sets and reps to create variations in load and intensity. At higher intensities our bodies provide energy to working muscles using an anaerobic chemical process. You know about this because you get very out of breath after a few seconds and your muscles fill up with lactic acid. The number of seconds is very, very relevant in most pool-based swimming events, as is the speed that you go – hence the importance of the Clock. To develop and refine their top speed competitive swimmers do short, fast reps with lots of recovery.
The key to being competitive in ‘slightly longer’ anaerobic races (i.e. most swimming races, as they’re over 30 seconds long) isn’t just speed, it’s sustaining speed as the pain builds up. To develop this lactate tolerance swimmers do fast reps with short recoveries.
If swimmers could just do fast reps they would. But the energy cost is too high and they need much more time in the water to perfect their technique so they do a lot of swimming at very low intensity.
Triathletes, on the other hand, race for much longer and use their aerobic energy systems. The build up of lactate is not the limiting factor. Anaerobic swimming efforts are essential for developing speed, but if your total race time is anything over, say, 45 minutes your ‘race pace’ is just BELOW your anaerobic threshold (or critical swim speed – CSS). Triathletes do long sets of reps at around CSS with short recoveries. Ideally the reps are long too (400m), but crowded lanes can make that difficult and shorter reps with, say, five-second recoveries can work just fine. And doing longs sets as 100s, or even 50s, helps pace awareness and management (the Clock again).
Getting the same training effect from open water swimming means training at the same intensities, just without the Clock and the measured distance. Unless your open water venue has accurately measured markers you should forget about comparing speeds and times with the pool, but if it has any markers (typically buoys) you can use those to create reps. If they are too far apart you can use your watch if it bleeps, or count your strokes or your breaths. You know how many strokes each length of the pool takes you (don’t you?), so you can do comparable length efforts.
Unless it’s too cold there’s also no reason why you can’t do stroke development and technique work in open water: drills and kick.
In short your can replicate nearly every aspect of your pool training in open water. There are a few tips (not-so) buried in the text above. Plan your session before you go: warm up, drills, set, subset, warm down, and then, if you are a triathlete, fast exit & wetsuit off!